This invention relates to cameras, particularly those having viewfinders presenting object images together with exposure information.
To exhibit exposure information, such as shutter speed, stop value, focusing distance, or other information in the viewfinder of a single lens camera, plates carrying such exposure information have been inserted between a focusing plate and a condenser lens. The plate is illuminated by a portion of the light flux which passes through an objective lens and is reflected by a mirror. The illumination makes the impressions upon the plate visible in the viewfinder.
In prior art systems of this type dust often intrudes into the image area.
Where the image area on the screen supports optical projections, such as the type that form Fresnel lenses, preventing dust accumulation is not only troublesome, but may be destructive to the projections themselves.